A. Field of the Invention
This invention relates to flame retardant synthetic polymers which find particular application in the production of filaments and fibers for use in the textile industry.
B. Description of the Prior Art
Numerous procedures have been proposed for conferring flame retardance on melt extruded filaments or fibers for use in the textile industry, such as the construction of carpets. One procedure has been to incorporate flame retardant materials into the polymer used to make the filaments or fibers by extruding the flame retardant material with the polymer.
Although this procedure has proven useful in certain instances, certain problems have remained. For instance, a number of flame retardant materials, when extruded with the polymer, result in finished polymers having an undesirably colored surface. Furthermore, resulting filaments containing the flame retardant materials, in many cases, have undesirable surface properties such as sensitivity to heat and light. Still further, many times the extruded material containing the synthetic polymer and flame retardant material is sensitive at the surface when the filaments are processed such as by passing them over guides, drawing them, or thermally treating them.
Another problem associated with a number of commercially available flame retardant materials is that it is necessary to incorporate large amounts, i.e., 20 to 40% by weight of the flame retardant, into the synthetic polymer. As a result, the physical properties of the synthetic polymer are modified which can result in the production of inferior fibers. Also, the incorporation of large amounts of flame retardant is uneconomical.
The term fiber as used herein includes fibers of extreme or indefinite length (i.e., filaments) and fibers of short length (i.e., staple). The term yarn, as used herein, means a continuous strand of fibers.
Carpet made from fibers of synthetic polymers, such as nylon fibers, is a popular floor covering for both residential and commercial applications. The typical carpet for residential applications has a primary backing material such as polypropylene, stretched with closely spaced erect loops or cut loops of yarn which extend upwardly from the backing to form a tufted structure (i.e., pile).
It is important that carpet have a combination of qualities, including safety, and aesthetically pleasing. Therefore, it is important that the fibers used for the carpet be fire retardant and not contain a significant amount of undesirable surface properties.
Thus, there is a need for materials which impart flame retardance to synthetic polymers used for fiber or yarn production without a concomitant reduction of physical properties of the fiber or yarn and which are effective in minor amounts such that commercially acceptable products are produced.